Customise size of pkgacct --split output files

I have a cron script running on a cPanel-powered server that runs

pkgacct each day then transfers the resulting files to an Amazon S3

server for backup purposes.

I was using the built-in unix "split"

command to do this but this was causing the server to run out of space

so I've switched to using pkgacct --split to do so.

This generates 100MB files, but it'd be handy to be able to customise the size of these files so that I could transfer fewer, larger, files.